Data from: Long-distance gene flow outweighs a century of local selection and prevents local adaptation in the Irish famine pathogen Phytophthora infestans

Sustainably managing plant resistance to epidemic pathogens implies controlling the genetic and demographic changes in pathogen populations faced with resistant hosts. Resistance management thus depends upon the dynamics of local adaptation, mainly driven by the balance between selection and gene flow. This dynamics is best investigated with populations from locally dominant hosts in islands with long histories of local selection. We used the unique case of the potato late blight pathosystem on Jersey, where a monoculture of potato cultivar ‘Jersey Royal’ has been in place for over a century. We also sampled populations from the coasts of Brittany and Normandy, as likely sources for gene flow. The isolation by distance pattern and the absence of genetic differentiation between Jersey and the closest French sites revealed gene flow at that spatial scale. Microsatellite allele frequencies revealed no evidence of recombination in the populations, but admixture of two genotypic clusters. No local adaptation in Jersey was detected from pathogenicity tests on Jersey Royal and on French cultivars. These data suggest that long-distance gene flow (~ 50/100 km) prevents local adaptation in Jersey despite a century of local selection by a single host cultivar and emphasize the need for regional rather than local management of resistance gene deployment.可持续管理植物对流行性病原菌（epidemic pathogens）的抗性，需调控面临抗病寄主的病原菌种群的遗传与种群动态变化（demographic changes）。因此，抗性管理取决于本地适应（local adaptation）的动态过程，而该过程主要由选择压力与基因流（gene flow）之间的平衡所驱动。此类动态过程的最佳研究载体，为拥有长期本地选择历史的岛屿上、源自当地优势寄主的病原菌种群。本研究选取泽西岛的马铃薯晚疫病病害系统（potato late blight pathosystem）作为独特研究案例——该岛的马铃薯品种"泽西皇家"（Jersey Royal）已连续单一种植超一个世纪。本研究同时从布列塔尼与诺曼底海岸采集病原菌种群，将其作为潜在的基因流来源种群。距离隔离（isolation by distance）模式分析结果，以及泽西岛与邻近法国采样点间未检测到遗传分化（genetic differentiation）的现象，均表明该空间尺度下存在基因流。微卫星等位基因（microsatellite allele）频率分析显示，各病原菌种群未出现重组（recombination）迹象，但存在两个基因型簇（genotypic clusters）的遗传混合现象。通过对"泽西皇家"及法国马铃薯品种的致病性测定（pathogenicity tests），未检测到泽西岛病原菌种群存在本地适应现象。上述研究结果表明，尽管该岛已通过单一寄主品种实施了长达一个世纪的本地选择，但约50至100公里的长距离基因流仍阻碍了本地适应的发生；同时本研究也强调，抗性基因部署应采用区域化管理而非本地化管理策略。